Narodowe Siły Zbrojne (English National Armed Forces, NSZ) was one of the Polish armed underground guerilla organizations, fighting Nazi German occupation in General Government.

It occupied the extreme right wing of political spectrum. Its program included fighting against Nazi Germany and Stalinist Soviet Union for the independence of Poland, keeping the Second Polish Republics pre-war eastern border and gaining territories of current Poland in the west.

The NSZ has been accused of chauvinism and anti-Semitism, however this has been proven to be communist propaganda. Some historians believe that the NSZ murdered hundreds of Jews who sought refuge in the forests. NSZ itself underlined, that it fought with Soviet partisants, many of them of Jewish origin. It also fought with the Polish communist partisans of Armia Ludowa (AL). Thanks to the policy of non-cooperation with the Soviets and unlike Home Army (AK), that was completely transparent to Soviet security services, NSZ remained a military and political power when Poland was taken over by the Red Army. The NSZ struggled against the new regime, while allegedly continuing to murder Holocaust survivors, whose as NSZ believed were the base for communist government. The members of NSZ were persecuted in the stalinist years after the war.

NSZ was created on September 20th, 1942. It reached about 70,000 members. Part of NSZ joined the Armia Krajowa in March 1944. NSZ units took part in the Warsaw Uprising. In January 1945, the NSZ Holy Cross Mountains Brigade (Brygada Świętokrzyska) retreated before the Red Army with the Germans approval, into the German protectorate of Bohemia and Moravia. It, however, fought against Germans again in May 5th, 1945 in Bohemia, when NSZ freed women from a concentration camp in Holiszowo. The brigade suffered heavy casualties.

Commanders: colonel Ignacy Oziewicz colonel Tadeusz Kurcyusz colonel Stanislaw Kasznica